2005 Chevy Cobalt Car running hot and making a vacuum noise

2005 CHEVROLET COBALT
65,000 MILES • 4 CYL • FWD • MANUAL
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WRE06
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Around two weeks ago my car started making a vacuum noise under load. The noise sounds like air leaking somewhere, if I accelerate with out downshifting the noise becomes very pronounced. Also, around the same time my engine started running much warmer than normal. I have no codes but my coolant gauge, which historically reads 187-190, now approaches around 220 every time I enter stop and go traffic. Could these be related? I checked the intake, and no holes are evident, and the seal from the intake to the throttle body is tight. I do have a slight oily residue on the inside of my throttle body, I'm not sure if this is normal. I checked the PCV system, and it appears to be operating normally.
Dec 18, 2008 at 5:30 PM
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BUDDYCRAIGG
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is your idle any higher?

you are describing a vacuum leak.

there are many ways to check for a vacuum leak.
i use a propane torch BUT DONT LIGHT IT.
i move it around everything in the intake system and hoses.
if you get to a spot that the engine rpm changes, then you are really close.

then i stick one end of a 3 foot long hose in my ear and move the hose around in that area until i can hear the sucking sound.

good luck
Dec 18, 2008 at 9:20 PM
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WRE06
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I was not able to locate the leak using the described methods. Any other suggestions? Is an oily residue inside the throttle body normal?
Feb 3, 2009 at 3:51 PM
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BUDDYCRAIGG
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find a repair shop that can do a "smoke test"

they blow pressurized smoke in to the suspect areas and the smoke will come out the leak.

should cost $80-$100.
but that's a lot cheaper than the machine.
Feb 4, 2009 at 12:08 AM